This invention relates to an improved automatic sewing machine for sewing large articles, in lock-stitch or chain-stitch, employing two completely different upper and lower mechanisms which are separately powered, wherein there is no continuous mechanical, electrical, hydraulic or other fixed connection between the upper and lower mechanisms required. An open notched needle carries the thread loop through the sewing material, and leaves a loop extending through the material as the needle retracts. An open notch in the needle enables the needle to be re-threaded during each stroke of the needle. A rotating bobbin assembly is provided with a unique bobbin case support means. The bobbin assembly dispenses bobbin thread to create a lock-stitch. A looper having two forked arms passes the needle thread around the bobbin case. The position of the needle determines the timing of the looper actuation. The needle position is sensed through the material being sewn. The material is advanced by pinching the material between adjacent wheels and rollers, or by rotating belts.